The present invention relates to a comminuting device for metal turnings with a driven rotor located in the housing of the comminuting device, on which rotor at the outlet side at least one precomminuting arm is placed, whose precommuniting knife cooperates with comminuting bars arranged on the housing and on which rotor on the outlet side a number of peripherally spaced rotor knives of a fine comminuting section are located, the comminuting edges of which cooperate with the comminuting edges of a number of peripherally spaced stator knives in the comminuting device housing.
A comminuting device for metal turnings of this type is to be seen in the German Offenlegungsschrift specification 2,547,980, corresponding to U.S. Pat. No. 4,140,282 in the case of which the comminuting device housing is formed like a letter U or of a trough in cross section at a right angle to the rotor axis and the top flat side of the comminuting device housing is in the form of a door. The inner wall face of the comminuting device housing runs generally parallel to the rotor axis. For this reason the turnings comminuting device does not have any constriction in the direction of the flow of material. The rotor is driven by way of a slipping clutch to prevent damage in the event of an overload or if the rotor is jammed. The drive is so controlled that if the rotor jams, the direction of rotation is reversed so that the rotor may work itself free again. Using such a reversing drive means that even coarse lumps, which have blocked the rotor in the fine comminuting section, are able to make their way to the outlet. However this measure is not always successful, more specially if the lump is larger than the gap between the rotor knife and the stator knife of the fine comminuting section. In such a case the turnings comminuting device has to be turned off and the top door of the housing opened so that the comminuting space may be at least partly emptied by hand and the lump taken out of the comminuting space. Since the turnings have sharp edges, the workers have to wear protective gloves for this work. Such operations are slow and for this reason mean that the plant is at stillstand for some time.